1) A racing car of mass 500 kg, including driver but not fuel, decelerates from a speed of 50 m s^-1 to 30 m s^-1 when approaching a bend.

The brakes exert a fixed retarding force of 7000 N. The time for the car to decelerate when it is almost out of fuel is t₁. The time for it to decelerate when it has a full load of 130 kg of fuel is t₂.

What is the difference (t₂ – t₁) in the two timings?

2) A light rod is acted upon by three forces P, Q and R.

Which diagram shows the position and direction of each of the forces when the rod is in equilibrium?

3) A man throws a stone vertically upwards.
Ignoring the effect of air resistance, which row describes the magnitude and direction of the force acting on the stone after it leaves the man's hand?

4) The following graphs describe the motions of three objects.

Which of the above graphs show(s) that a constant resultant force is acting on the object?

5) Jane stands on a bathroom scale to find out her weight.

Which of the following pairs of forces is/are action and reaction pairs?
(1) The force exerted by Jane on the scale and the force exerted by the scale on Jane.
(2) The gravitational force exerted by the Earth on Jane and the force exerted by the scale on Jane.
(3) The gravitational force exerted by the Earth on the scale and the gravitational force exerted by the Earth on Jane.